The occurrence of ovarian cancers in human and experimental tumors in rats can be correlated with several conditions which prevent normal cyclic functions, as well as conditions associated with elevated serum levels of follicle-stimulating hormone (FSH) and luteinizing hormone (LH). This project proposed to combine these conditions by parabiotically joining persistent-estrus androgenized female and castrated male rats. The gonadotropic (FSH, LH, Prolactin) and steroid (estrogen, progestin, androgen) concentrations in their sera will be measured by immunoassays prior to, during, and after ovarian tumors have developed. In addition the effect of cyclicity, induced by exogenous LH or hypothalamic releasing hormone, upon these hormones, the tumorigenic process, and the fully developed tumors will be studied. The results will contribute to our knowledge of the endocrine environment conducive to tumor formation and the effect of the tumors on this environment. Furthermore, techniques will be employed to interfere with the tumorigenic process.